Facsimile recorder



Dec. 25, 1945. A B AIN I 2,391,768

FACSIMILE RECORDER Filed Jan. 30, 1941 2 Sheets-Sheet l Dec. 25, 1945. A. BLAIN FACSIMILE RECORDER Filed Jan. 30, 1941 2 Sheets-Sheet 2 Patented Dec. 25, 1945 FACSIMILE nnooitnsn Albert Blain, Philadelphia, Pa., assignor to Radio Corporation of America, a corporation of Delaware Application January 30, 1941, Serial No. 376,615 2 Claims. (Cl. 234-68) This invention relates to facsimile systems and more particularly to facsimile recorders.

In facsimile systems wherein a drum having a helical edge is adapted to rotate in synchronism with a drum supporting the record to be transmitted, the record may be reproduced on a record surface by causing the helical edge to act upon the surface in accordance with the signals received from the facsimile transmitter.

Heretofore, it has been the common practice to employ a drum having a helical edge in cooperation with a straight printer bar which is adapted to act upon the picture recording surface in accordance with the facsimile signal.

It is. desirable to decrease the size of each recording spot in order that the detail of the recording may be improved. It may be said that the detail of the-recording is very nearly inversely proportional to the longest dimension of each recording spot. In order to improve the detail of the picture, it therefore becomes necessary to decrease the longest dimension of the area of each recording spot.

It may be readily seen that the area of each recording spot in facsimile recorders employing a helical edge associated with a straight printer bar takes the form of a diamond rather than a small square or rectangle. It has been found that the area of the recording element may be made more nearly to approximate the shape of a square by increasing the diameter of a drum such that the angle of intersection between the helical edge and the printer bar is increased to approach 90. 11;

is, however, impossible to even theoretically provide a drum large enough that the angle of intersection between its helical edge and it associated printer bar will be 90. Furthermore, there are disadvantages which accompany the increased diameter of the rotating drum. For example, the equipment is made bulky and the increased diameter increases the inertia of the rotating drum which makes it more difficult to keep the receiver drum in synchronism with a, transmitter drum not particularly adapted to maintain a constant speed due to the nature of the equipment such as used in remote pickups.

Although this invention may be adapted for mechanical printing or printing on a record surface by mechanical pressure upon a transfer paper such as shown and described in the Young Reissue Patent 20,152, patented October 27, 1936, for the purpose of illustration a system of electrochemical recording has been adapted. It has hitherto been proposed to reproduce records by impregnating paper with a substance which will be discolored under the influence of an electric current and to apply this current at successive single small areas of the paper at a time, causing said area to progress systematically over the paper and so varying the current that, at each position of said area, it shall be proportional to the degree of darkening necessary to reproduce the record.

According to this invention, a pair of adjacent helical electrodes are adapted to revolve about parallel axes and intersect on a recording surface such that the angle of intersection between the helical electrodes is great and the area caused by the intersection takes the for-m of a square or small rectangle rather than a diamond, due to the large angle of intersection between the cooperating printing elements.

The primary object of this invention is to provide an improved facsimile recorder.

Another object of this invention is to improve the detail of the recording.

Another object of this invention is to decrease the area of the recording spot.

' Another object is to decrease the diameter (and inertia) of helix drums, .thus permitting better synchronizing control of the facsimile system.

Other and incidental objects of the-invention will be apparent to those skilled in the art from a reading of the following specification considered in connection with the accompanying drawings in which v Figure 1 is an end view of a facsimile recorder,

Figure 2 is a sectional view of Figure 1,

Figure 3 is a front view showing the printer drums and helical electrodes, and

Figure 4 is a plane view of the facsimile recorder.

Referring now in more detail to Figure l, a spool l carries a roll of paper or other recording surface 3 and is mounted at one end of the recorder. Below the spool l, a tank 5 is provided with a guide roller 1 under which the paper 3 from the spool l is passed such that it will be immersed in the liquid in tank 5, which liquid is adapted to sensitize the paper 3 such that it will change its color upon the application of an electric current. This may be accomplished by the means and methods such as shown and described in Zworykin Patent 1,909,142, patented May 16, 1933.

The paper 3 then passes up and over a stationary guide tube 9 which is positioned around a shaft [0. It then passes under a guide rod l I and between the drums l3 and I5. Drums l3 and ii are composed of an insulating material. Drum 30. Drum 13 and gear 3| are mounted on shaft 32. The gear 33, mounted on shaft I0. engages the gears 29 and 3|.

Figure 2 shows a guard member 35 which covers the drum l3 whereby the'spiral electrode i1 is guarded from mechanical damage and the operator is protected from receiving an electrical shock from the exposed-and charged electrode l1.

Figure 3 shows a front view of the drums l3 and 15. The helical electrodes [1 and I9 are supported upon the surface of the drums l3 and 15, respectively. It will be noticed that the angle of intersection between the two helical electrodes is necessarily twice as great as it would be if oneof the drums l3 or I5 were replaced by the customary printer bar.- Itis thus apparent that the area of intersection between the two ,heli'cal electrodes l1 and 49 will cover a smaller area and the shape of the area will be more like that of a square rather than a diamond. Each helical electrode makes one complete revolution about its associated drum. The relative angular position of the drums l3 and I5 is adjusted such that .the two helical electrodes will intersect.

Assuming the drums to rotate, as for xample,

in the directions indicated by the arrows, the point of contact between the two helical electrodes will move in the direction of the horizontal arrow (Figure 1). This movement will be from one end of the drums to the other end of the drums. As the point of intersection approaches one edge of the paper which is interposed between the printer drums, the electrodes will intersect again at the other edge of the paper.

If it is desired to have the drums rotate in opposite directions, it is necessary to have the spiral of one drum run in the opposite direction of the other. i

Figure 4 shows the paper and the drum drive mechanism. A motor 3'! which is kept in synchronism with the motor at the facsimile transmitter is mechanically coupled to the shaft Id upon which is mounted the gear 33 of the wellknown split gear type in order that the gear 33' may engage the gears 3| and 29 and allow the necessary adjustment of the relative angular position of the two drums. Gear 3i drives the upper drum l3which contains the helix H. The

lower gear 29 drives the drum, l5 which is fixed, v

to a shaft 30 upon which is mounted a worm gear 39 which engages the gear 4| mounted on the shaft 12, containing the worm gear 53. The

gear 43 engages a gear 45 on a shaft including the sheet drive roller 23.

- As the paper is passed through the solution contained in tank 5; it is sensitized such that,

if an electric. current is passedtherethrough, a

mark will appear at thepoint of contact with the electrode charged positively with respect to its cooperating electrode. The paper thus sensitized passes between drums l3 and i5, rotating.

in directions shown by the arrows and at a predetermined rate. It is preferable that the drums rotate'in the same directions so that the tension producedby the friction between one drum and the paper is opposite in direction to the tension upon the paper produced by the other drum. This allows the movement of the paper to be easily controlled by the drive roller 23.

A facsimile signal representative of the record to be made is applied to electrodes l1 and 19. The drum l3 contai,ns a metallic slip ring 41 which is in contact with its associated electrode ll. Drum l5 has a similar slip ring, not shown. A terminal or brush 49 is adapted to engage the metallic ring 41 and is insulated from the frame such that a. signal may .be applied to the lectrodes while the drums are rotating. The lower drum l5 has a similar brush cooperating with its slip ring.

A transmitter adapted to transmit such facsimile signals is shown and described in an article entitled, "Facsimile transmission and reception, loy- Maurice Artzt in the Electrical Engineers Handbook.

As the paper slowly moves between the rotating drums l3 and E5, the point of intersection between the paper and the electrodes l7 and I9- scans the paper from one side to the other side and forms a continuous image thereon. It fol lows that, as a signal is applied to the electrodes l1 and I9, there will be a record formed on the paper representative of a train of facsi'mile Sigrials applied to the electrodes.

While one system for carrying this invention into effect has beenindicated and described, it will be apparent to one skilled in the art that this invention is by no means limited to the particular organization shown and described, but that many modifications may be made without departing from the scope of this invention as set forth in the appended claims.

E claim as my invention:

1. In a facsimile recording system, the combination of a pair of adjacent helical electrodes adapted to rotat about parallel axes, means for applying a signal current to said electrodes, means for feeding a record receiving sheet between and in contact with adjacent points on said electrodes, and means for causing said electrodes to act upon said sheet in response to said signal current.

2. In a facsimile recorder, the combination of a pair of adjacent rotatable drums, a helical electrode on the surface of each of said drums, a slip ring at one end of each of said drums. a connection between said ring and its associated electrode, means for applying a signal current to said slip rings, and means for feeding a record receiving sheet between and in contact with adjacent points on said electrodes.

ALBERT BLAIN. 

